In the area of optical applications, the refractive index is an important material property. Thus, it plays an important role, for example, for the production of optical components, such as lenses, prisms and optical coatings (U.S. Pat. No. 5,916,987) or for the production of a contrast in holographic materials (U.S. Pat. No. 6,780,546). For such and similar applications, there is a need to be able to adjust the refractive index in a targeted manned, for example by admixing components having a high refractive index.
For the abovementioned fields of use, polymers of olefinically unsaturated compounds, such as, preferably, (meth)acrylates, are typically used. In order to reach the refractive index of 1.5 or higher, halogen-substituted aromatic (meth)acrylates or special alkyl methacrylates described in U.S. Pat. No. 6,794,471 can be used. Particularly the latter are disadvantageous owing to their complicated preparation.
The class of substances consisting of the urethane (meth)acrylates is well known per se from the area of coating technology. According to the prior art, however, the extent to which these are suitable for the production of data media, in particular those for holographic storage methods, is not known.